Hydraulic fuse



1944- R. L. LAVENDER HYDRAULIC FUSE Filed Sept. 19, 1942 INVENTOR Patented Oct. 10, 1944 UNITED HYDRAULIC FUSE Robert L. Lavender, Cleveland, Ohio, assignor to The Marquette Metal Products Company,

Cleveland, Ohio, a corporation of Ohio Application September 19, 1942, Serial No. 459,051

3 Claims.

This invention relates to a device for safeguarding and/or preventing fouling of hydraulic machinery and apparatus or parts thereof in the event of accidental release of pressure in a hydraulically operated instrument-or in the feed line of such instrument. The device is analogous in operation to an electric service line fuse and, for convenience, it will be referred to herein as a hydraulic fuse. The above indicates the general object.

The objects further include the provision of a hydraulic fuse which is compact and simple in construction; easy to build and install; capable of functioning properly in any mounted position; unlikely to fail to operate when the occasion requires operation, and which will b positive in action in a manner to block a hydraulic feed line upon the occurrence of sudden surge in the line or critical reduction of normal back pressure or flow resistance therein.

A special object is to provide a positively acting hydraulic fuse which can be reconditioned quickly for further service after it acts to block a hydraulic feed line; and a further object is to provid a hydraulic fuse in which the releasing element which causes the line to become blocked is an inexpensive filament or rod which is pulled apart and is easily accessible for replacement after the cause of breakage has been ascertained and remedied.

I am aware of the fact that spring operated devices have been proposed to safeguard hydraulically operated apparatus against line breakage,

suddenly occurring leaks etc.; and that a device employin a frangible plate which requires sufficient release of force to shatter it are already known in the art. The spring operated devices are impositive in operation and sometimes reset themselves before the cause of the trouble has been ascertained; and the frangible plate arrangements require so much force to break them that they cannot serve the essential purpose in actual practice because a force which, to be efiective must be released because of fracture due to compression beyond the intended limit may vary over a wide range. If, on the other hand, the fracturable element is subject to tension (pulled apart) in order to cause functioning at the critical time, said element can be made with much less expense and can be rnade capable of responding to a. much more delicate safety limit in respect to the apparatus to be safeguarded thereby. Furthermore, a device which acts consequent upon release of predeterminable tension can more readily be replaced and can be operated to stop all flow in a hydraulic supply line without requiring any special reception pocket for the fractured parts.

' In the accompanying drawing Fig.1 is a side elevation of one form of hydraulic fuse; Fig. 2 is a plan view thereof; Fig. 3 is a sectional view as indicated at 33 on Fig. 2; Fig. 4 is a sectional view taken in two planes, substantially as indicated by the line 44 on Fig. 3, and Fig. 5 is a perspective view of one form of breakable or fracturable element of the device hereof.

Figs. 1, 2 and 3 show a hollow body I of generally cylindrical form having athreaded inlet portion 2 and similar outlet portion 3 adapted for receiving complementarily th'readed portions i and 5, respectively, of piping or tubing leading from a source of supply to a hydraulically operable instrument to be safeguarded etc. as outlined above. A detachable cover plate 6 closes one side of the body, being secured thereto as by a series of screws 1, or, optionally-for enabling more rapid detachment of the plate if desireda single screw may be employed at the center of the plate.

If a single screw or fastener is used then the joint surfaces between the cover plate and body would ordinarily require more elaborate sealing means to prevent leakage (e. g. require a compressible gasket of suitable form, not shown).

In Fig. 3 a central inlet orifice 9 opens into a relatively enlarged cylindrical valve chamber [0; and the hydraulic fluid can normally flow freely to the outlet orifice ll shown aligned with the inlet, past peripheral surfaces of a check valve plate l2, as around the sides, top and bottom of the plate (see Fig. 4)

The valve plate I2 is preferably of curved or crescent shape, as shown; is, in effect, pivoted to the body on a supporting pin l3 and is retained, normally, in the position in which shown in Fig. 3 by an elongated, breakable tension element l5, supported in part by the valve plate and in part by a pin or post l6 fixed inside the body 5 parallel to the pivot pin l3.

The breakable or readily frangible element l5, as shown, is a rod, pin or filament of relatively small cross section with a knob H on each end. The breakable rod l5, adjacent one knob thereof, lies in an open-ended slot H3 at the end of the valve plate which lies remotely of the pivot pin 13, and, adjacent the other knob, lies in an openended slot I9 in the pin or post l6 (open at the left end Fig. 4). As shown in Fig. 4, the slots 18 and I9 are at right angles to each other, said arrangement of slots maintaining the breakable rod in valve-plate-retaining position irrespective of the position in which the hydraulic fuse happens to be placed, and also, as will be explained presently, enabling the breakable element to be removed. and replaced readily after breakage thereof occurs.

The breaking point of the element [5 in case it is a rod may be predetermined, if desired, by

notching the rod as at 20, Fig. 5.

The retaining post I6 is fixed at one end to the rear wall of the body I (as by a press fit in the hole 2|) and the opposite open-slotted end of the retaining post, as shown in Fig. 4, readily slides into a socket 22 in the cover plate. The pivot pin 13 is attached to the cover plate atone end (as by a press fit in opening 23), and the opposite end enters a pilot socket 24 in the rear wall of the body I.

Preferably thepivot pin i3 has an enlarged shoulder portion 2'5 beyond the valve plate l2 in order that the valve plate will necessarily be removed from operating position when the cover plate is detached from the body. Removal of the cover plate, after the element l5 breaks, carries one end of the element l5 out of the body I, along with the valve plate. The other end of the breakable element can then be removed easily, without requiring a special tool from the slot in the retainer post 16, as will be obvious from Fig. 4.

To replace the broken element l5, one end of a new element I5 is placed in the open slot 18 of the valve plate and the other end of the element is then slid into the open slot IQ of the retainer post I6 as the cover and valve plate assembly is returned to original position.

blade effect) so that, even if the by-passage spaces around the valve plate l2 are slightly Special by-passage spaces of adequate projected area may be formed by centrally recessing the body and coverplateas at 26 and 21 respectively (counterbore effects). The circular margins radially outwardly beyond the recesses (28 and 29) constitute guiding lands for the valve plate end or side portions as will be evident from Figs. 3 and 4. The total area of by-passage at the margins of the valve plate are exaggerated in Fig. 4 for illustrative purposes. The total by-passage areaaround the valve plate I2. is, of course, determined by the sizes of the fluid inlet and outlet passages 9 and H; and said total area should not be materially greater than either, or at least not materially greater than the area of the outlet.

The convex face of the valve plate 12 has a,

larger in total projected area than the inlet or outlet opening areas, the device will function as described above when the normal resistance to. flow beyond the outlet ll fails to obtain.

I claim:

1. A hydraulic fuse comprising a hollow body having an inlet, an outlet and an enlarged chamber therebetween, a movable valve member in the chamber adapted to seal the outlet, means supporting the member for movement from unsealing position to sealing position, a slot in the valve member'extending in a direction transverse to the direction of movement of the valve member, a double headed, elongated breakable holding element detachably occupying the slot with one head abutting the valve member adjacent the slot thereof, a retainer having a slot for detachably receiving another portion of the holding element and having a surface adjacent said slot for abutting the other head, said slots extending transversely of each other in a manner to prevent accidental detachment of the holding element from the valve member and retainer irrespective of the position in which the fuse is mounted.

2. The arrangement according to claim 1 wherein the valve member is pivotally mounted on a cover plate of the hollow body and its slot is an open ended slot for the breakable holding element, and the retainer is a pin rigid with the hollow body inside thereof and projecting toward the cover plate, the slot of the retainer pin extending lengthwise of the pin and being open at the end of the pin which lies adjacent the cover plate.

3. A hydraulic fuse comprising a hollow body with a generally cylindrical chamber therein, a detachable cover plate constituting one end wall of the chamber, inlet and outlet passages for fluid in the body disposed substantially diametrally of the chamber, a valve plate having sealing means for the outlet, a pivot pin on the cover plate parallel to the axis of the chamber and constituting a mounting for the valve plate by which the valve plate is removable from the chamber when the cover plate is detached, a post carried by the end wall of the chamber opposite the cover plate, and breakable means readily associable with the valve plate and post when the cover plate is moved to chamber closing position.

ROBERT L. LAVENDER. 

